Dihydromyricetin Enhances Exercise-Induced GLP-1 Elevation through Stimulating cAMP and Inhibiting DPP-4

Grain bound polyphenols: Molecular interactions, release characteristics, and regulation mechanisms of postprandial hyperglycemia

Frequent postprandial hyperglycemia causes many chronic diseases. Grain polyphenols are widely recognized as natural active ingredients with high potential to treat chronic diseases due to their excellent postprandial hyperglycemic regulating effects. However, previous studies on polyphenols in grains mainly focused on the functional properties of free polyphenols and the extraction and physicochemical properties of bound polyphenols, ignoring the functional properties of bound polyphenols. Comprehensively understanding the binding properties of grain bound polyphenols (GBPs) and their mechanisms in regulating blood glucose levels is essential for developing and applying grain resources. This review summarizes the molecular interactions between GBPs and grain components and their effects on release characteristics and bioavailability at various stages. Meanwhile, the review focuses on elucidating the regulatory mechanism of post-release GBPs on postprandial hyperglycemia levels, incorporating insights from molecular docking, the gastrointestinal-brain axis, and gut flora. GBPs slow food digestion by occupying the active site of digestive enzymes and altering the secondary structure of enzymes and the hydrophobic environment of amino acid residues to inhibit enzyme activity. They modulate intestinal epithelial transport proteins (SGLT1, GLUT2, and GLUT4) to limit glucose absorption and increase glucose consumption. They also stimulate the release of short-term satiety hormones (CKK, GLP-1, and PYY) through the gastrointestinal-brain axis to decrease post-meal food intake. Furthermore, they optimize gut microbiota composition, promoting short-chain fatty acid production and bile acid metabolism. Therefore, developing functional foods with glucose-modulating properties based on GBPs is crucial for obesity prevention, diabetes management, and low-GI food development.

Dihydromyricetin Promotes Glucagon-Like Peptide-1 Secretion and Improves Insulin Resistance by Modulation of the Gut Microbiota-CDCA Pathway

Insulin resistance is a common metabolic disease, and its pathogenesis is still unclear. The decrease of glucagon-like peptide-1 (GLP-1) level mediated by the alteration of gut microbiota may be the pathogenesis. The study was to investigate the regulatory effect of dihydromyricetin (DHM) on GLP-1 level and insulin resistance induced by high-fat diet (HFD), and to further explore its possible molecular mechanism. Mice were fed an HFD to establish the model of insulin resistance to determine whether DHM had a protective effect. DHM could improve insulin resistance. DHM increased serum GLP-1 by improving intestinal GLP-1 secretion and inhibiting GLP-1 decomposition, associated with the alteration of intestinal intraepithelial lymphocytes (IELs) proportions and decreased expression of CD26 in IELs and TCRαβ+ CD8αβ+ IELs in HFD-induced mice. DHM could ameliorate GLP-1 level and insulin resistance by modulation of gut microbiota and the metabolites, particularly the regulation of chenodeoxycholic acid (CDCA) content, followed by the inhibition of farnesoid X receptor (FXR) expression in intestinal L cells and increased glucagon gene (Gcg) mRNA expression and GLP-1 secretion. This research demonstrates the role of "gut microbiota-CDCA" pathway in the improvement of intestinal GLP-1 levels in HFD-induced mice by DHM administration, providing a new target for the prevention of insulin resistance.

Chemerin loss-of-function attenuates glucagon-like peptide-1 secretion in exercised obese mice

AIMS

To investigate the role of chemerin reduction in mediating exercise-induced Glucagon-like peptide-1 (GLP-1) secretion and the amelioration of pancreatic β-cell function in obesity.

MATERIALS AND METHODS

Obesity models were established using wild-type and chemerin systemic knockout mice, followed by 8 weeks of moderate-intensity continuous aerobic exercise training. Serum chemerin levels, GLP-1 synthesis, glucose tolerance, pancreatic β-cell function, structure, and apoptosis were assessed. In vitro experiments were conducted on STC-1 cells, derived from murine intestinal endocrine cells, to evaluate GLP-1 secretion following exogenous chemerin treatment. Additionally, colonic tissue inflammation and apoptosis were analyzed using qPCR and TUNEL staining.

RESULTS

In obese wild-type mice, moderate-intensity aerobic exercise significantly reduced serum chemerin levels, enhanced GLP-1 secretion, and improved glucose tolerance, pancreatic β-cell structure, function, and apoptosis. These effects were absent in obese chemerin knockout mice. Exogenous chemerin treatment reduced GLP-1 secretion in STC-1 cells. Furthermore, the beneficial effects of exercise on colonic inflammation and apoptosis observed in wild-type mice were abolished in chemerin knockout mice.

CONCLUSION

Reduction of chemerin is crucial for the beneficial effects of aerobic exercise on GLP-1 secretion and pancreatic β-cell function in obesity. The mechanisms behind these effects may involve improvements in colonic inflammation and apoptosis. These findings offer new insights into the molecular mechanisms through which exercise improves obesity-related metabolic dysfunction.

Pea protein hydrolysate stimulates GLP-1 secretion in NCI-H716 cells via simultaneously activating the sensing receptors CaSR and PepT1

Glucagon-like peptide-1 (GLP-1) plays a crucial role in regulating glucose homeostasis by stimulating insulin secretion and suppressing glucagon release. Our previous study observed that pea protein hydrolysate (PPH) exhibited the function of triggering GLP-1 secretion. However, the underlying mechanisms have not been revealed. Herein, the mechanisms of PPH-stimulated GLP-1 secretion were investigated in NCI-H716 cells. The PPH-induced GLP-1 secretion was reduced (p < 0.05) after adding the sensing receptor antagonists NPS-2143 and 4-AMBA, indicating that activation of both calcium-sensing receptor (CaSR) and peptide-transporter 1 (PepT1) was involved in PPH-triggered GLP-1 release. Moreover, the intracellular Ca2+ level increased by 2.01 times during the PPH-induced GLP-1 secretion. Similarly, the cAMP content also increased by 1.43 times after stimulation by PPH. The RT-qPCR results showed that PPH increased the gene expression of prohormone convertase 1/3 (PCSK-1) by 2.79-fold, which effectively promoted the conversion of proglucagon (GCG) to GLP-1. The specific pathway of PPH-induced GLP-1 secretion may involve both CaSR and PepT1 activation-induced Ca2+ influx and cAMP generation, which effectively enhanced the enzyme activity of prohormone convertase 1/3 (PCSK-1) and ultimately promoted GLP-1 secretion.

Targeting Autophagy: A Promising Therapeutic Strategy for Diabetes Mellitus and Diabetic Nephropathy

Diabetes mellitus (DM) significantly impairs patients' quality of life, primarily because of its complications, which are the leading cause of mortality among individuals with the disease. Autophagy has emerged as a key process closely associated with DM, including its complications such as diabetic nephropathy (DN). DN is a major complication of DM, contributing significantly to chronic kidney disease and renal failure. The intricate connection between autophagy and DM, including DN, highlights the potential for new therapeutic targets. This review examines the interplay between autophagy and these conditions, aiming to uncover novel approaches to treatment and enhance our understanding of their underlying pathophysiology. It also explores the role of autophagy in maintaining renal homeostasis and its involvement in the development and progression of DM and DN. Furthermore, the review discusses natural compounds that may alleviate these conditions by modulating autophagy.

Exercise in Diabetic Nephropathy: Protective Effects and Molecular Mechanism

Diabetic nephropathy (DN) is a serious complication of diabetes, and its progression is influenced by factors like oxidative stress, inflammation, cell death, and fibrosis. Compared to drug treatment, exercise offers a cost-effective and low-risk approach to slowing down DN progression. Through multiple ways and mechanisms, exercise helps to control blood sugar and blood pressure and reduce serum creatinine and albuminuria, thereby alleviating kidney damage. This review explores the beneficial effects of exercise on DN improvement and highlights its potential mechanisms for ameliorating DN. In-depth understanding of the role and mechanism of exercise in improving DN would pave the way for formulating safe and effective exercise programs for the treatment and prevention of DN.

Jian-Pi-Yin decoction attenuates lactose-induced chronic diarrhea in rats by regulating GLP-1 and reducing NHE3 ubiquitination and phosphorylation

Objectives

Jian-Pi-Yin decoction (JPY), a prescription derived from the traditional Chinese medicine Shen-Ling-Bai-Zhu-San, has shown good clinical efficacy in the treatment of diarrhea caused by lactose intolerance. However, the mechanism of action of JPY in the treatment of diarrhea is not fully understood.

Design

In this study, a rat diarrhea model was induced by high lactose feeding combined with standing on a small platform to investigate the ameliorating effect of JPY on hyper lactose-induced diarrhea in rats and its possible mechanism.

Methods

The rat model of hyper lactose diarrhea was given high, medium, and low doses of JPY and the positive control drug Smida by gavage for 1 week. At the same time, NA+-H+ exchanger 3 (NHE3) inhibitor Tenapanor was administered orally for 3 weeks. Body weight, food intake, water intake, grip strength, and severity of diarrhea symptoms were measured in rats throughout the study. The serum, colon, and jejunum tissues of the model and drug-treated rats were collected for histopathological examination and analysis of relevant indicators.

Results

JPY significantly alleviated the symptoms of fatigue, diet reduction and diarrhea in the model group. Glucagon-like peptide-1 (GLP-1) and cyclic adenosine monophosphate (cAMP) expression were also down-regulated after JPY treatment. JPY can significantly promote NHE3 in intestinal tissues of rats with diarrhea, and the mechanism is related to the decrease of GLP-1, inhibition of cAMP/PKA pathway activation, an increase of ubiquitin-specific protease 7 (USP7) and USP10 expression, and decrease of NHE3 ubiquitination and phosphorylation.

Conclusion

JPY can reduce the expression of GLP-1, reduce the ubiquitination and phosphorylation of NHE3, regulate the expression of NHE3, at least partly improve ion transport in the intestinal epithelium, and improve the imbalance of electrolyte absorption, thus significantly reducing the diarrhea symptoms of rats with high lactose combined with small platform standing.

Innovation

In this study, we explored the mechanism of intestinal GLP-1 activation of cAMP/PKA signaling pathway from multiple dimensions, and increased its expression by reducing phosphorylation and ubiquitination of NHE3, thereby treating chronic diarrhea associated with lactose intolerance.

Dihydromyricetin promotes GLP-1 release and glucose uptake by STC-1 cells and enhances the effects of metformin upon STC-1 cells and diabetic mouse model

BACKGROUND

Glucagon-like peptide-1 (GLP-1) is an intestinally produced hormone released by the L-cells to stimulate glucose-dependent insulin release. Vine tea, a traditional Chinese medicine made from the delicate stem and leaves of Ampelopsis grossedentata, has been reported to exert antidiabetic effects; however, the role and mechanism of dihydromyricetin, the main active ingredient of vine tea, remain unclear.

METHODS AND RESULTS

MTT assay was applied to detect cell viability. GLP-1 levels in the culture medium using a mouse GLP-1 ELISA kit. The level of GLP-1 in cells was examined using IF staining. NBDG assay was performed to evaluate the glucose uptake by STC-1 cells. The in vivo roles of dihydromyricetin in the diabetes mellitus mouse model were investigated. In this study, 25 μM dihydromyricetin, was found to cause no significant suppression of STC-1 cell viability. Dihydromyricetin markedly elevated GLP-1 secretion and glucose uptake by STC-1 cells. Although metformin increased GLP-1 release and glucose uptake by STC-1 cells more, dihydromyricetin further enhanced the effects of metformin. Moreover, dihydromyricetin or metformin alone significantly promoted the phosphorylation of AMPK, increased GLUT4 levels, inhibited ERK1/2 and IRS-1 phosphorylation, and decreased NF-κB levels, and dihydromyricetin also enhanced the effects of metformin on these factors. The in vivo results further confirmed the antidiabetic function of dihydromyricetin.

CONCLUSION

Dihydromyricetin promotes GLP-1 release and glucose uptake by STC-1 cells and enhances the effects of metformin upon STC-1 cells and diabetic mice, which might ameliorate diabetes through improving L cell functions. The Erk1/2 and AMPK signaling pathways might be involved.

Targeting the gut microbiota and its metabolites for type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a metabolic disorder characterized by hyperglycemia and insulin resistance. The incidence of T2DM is increasing globally, and a growing body of evidence suggests that gut microbiota dysbiosis may contribute to the development of this disease. Gut microbiota-derived metabolites, including bile acids, lipopolysaccharide, trimethylamine-N-oxide, tryptophan and indole derivatives, and short-chain fatty acids, have been shown to be involved in the pathogenesis of T2DM, playing a key role in the host-microbe crosstalk. This review aims to summarize the molecular links between gut microbiota-derived metabolites and the pathogenesis of T2DM. Additionally, we review the potential therapy and treatments for T2DM using probiotics, prebiotics, fecal microbiota transplantation and other methods to modulate gut microbiota and its metabolites. Clinical trials investigating the role of gut microbiota and its metabolites have been critically discussed. This review highlights that targeting the gut microbiota and its metabolites could be a potential therapeutic strategy for the prevention and treatment of T2DM.

Effect of Resistance Training with Different Set Structures on Neurotrophic Factors and Obesity-Related Biomarkers in Middle-Aged Korean Women with Obesity

This 12-week study investigates the effects of resistance training with different set structures on the plasma levels of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), and obesity-related markers in middle-aged Korean women with obesity. A total of 40 middle-aged women with obesity (mean age, 59.87 ± 2.80 years) were enrolled in this study; only 31 women were able to complete the 12-week exercise period. The participants were randomly divided into the following four groups: control (CON, n = 8), drop set system (Drop, n = 8), descending set system (Descend, n = 7), and ascending set system (Ascend, n = 8). Body composition was recorded, and blood samples were obtained and evaluated before and after the 12-week exercise period intervention. Two groups showed no significant differences in body weight, body fat percentage, and body mass index before and after the 12-week exercise period. However, significant differences were observed in the blood levels of BDNF, NGF, adiponectin, leptin, and glucagon-like peptide-1 (GLP-1). BDNF and NGF showed significant differences in both time and interaction effects. Post hoc analysis revealed that the Drop group had higher BDNF and NFG levels than those of the Ascend and CON groups, while there was a significant increase in the levels of these biomarkers in the Descend and Drop groups in the time comparison. Adiponectin levels also showed significant differences in both time and interaction effects. Post hoc analysis revealed that the Drop and Descend groups had higher adiponectin levels than those of the CON group. Leptin levels decreased significantly in the Descend and Drop groups over time. GLP-1 levels showed no significant differences between the groups; however, there were significant differences in both time and interaction effects. Post hoc analysis revealed that the Drop group had lower GLP-1 levels than those of the CON group. This study suggests that resistance training with different set structures can have varying effects on the blood levels of different biomarkers in middle-aged women with obesity. These findings have implications for exercise prescription, and may provide insights into the mechanisms underlying the beneficial outcomes of resistance training in middle-aged Korean women with obesity.